Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). ALEWIFE/BLUEBACK HERRING,

Abstract

Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. They are prepared to assist in impact assessment. The alewife and blueback herring, Alosa pseudoharengus and Alosa aestivalis, are important species in estuarine and marine ecosystems as links between the zooplankton they consume and top piscivores. Both anadromous and land-locked populations exist. Some individuals mature by age 3, and all mature by age 5. Repeat spawning is common. Spawning environments range from stream only a few centimeters deep to large rivers. Alewives will also spawn in ponds with an open connection to the sea. Blueback herring prefer spawning sites with fast currents and associated hard substrates, while alewives select a wider variety of sites, from standing water and oxbows to mid-river areas. Spawning occurs from April to July in the mid-Atlantic region; the onset and peak of alewife spawning precede those of blueback herring by 2 to 3 weeks. Larvae and juveniles remain in or near areas spawned before emigrating (as juveniles) to coastal areas between June and November of their first year. Emigration is apparently triggered by heavy runoff from rain and/or sharp decreases in water temperature. Adults overwinter offshoremore » to depths of at least 110 m. Nantucket Shoals, Georges Bank, and the Gulf of Maine are important overwintering grounds. Commercial and limited recreational fisheries for these species occur; total US landings in 1981 were 3754 mt, while foreign landings were 13.9 mt. Some eggs can hatch at water temperatures between 7/sup 0/ and 29.5/sup 0/C, but temperatures above 29.7/sup 0/C are lethal. Larvae need temperatures greater than 10/sup 0/C for proper development; upper lethal temperature is 31/sup 0/C. 93 references, 4 figures, 1 table.« less